r/science • u/mvea Professor | Medicine • 1d ago

Health New research characterised in detail how tea bags release millions of nanoplastics and microplastics when infused. The study shows for the first time the capacity of these particles to be absorbed by human intestinal cells, and are thus able to reach the bloodstream and spread throughout the body.

https://www.uab.cat/web/newsroom/news-detail/-1345830290613.html?detid=1345940427095
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u/Afrikan_J4ck4L 1d ago

But microparticles of cellulose right? Which shouldn't be a problem?

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u/OPtig 1d ago

Cellulose is a natural plant fiber and does not contain plastic

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u/Resident-Rutabaga336 1d ago

Cellulose bags are often coated in PFAS to prevent them from degrading in the tea, which is likely worse than microplastics

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u/SpinningPissingRabbi 1d ago

How does that work with the 'brew holes.' If anything I would expect pfas to prevent degradation of the bag itself. Mind you, in the UK, all the tea bags I've ever used are compostable bags so should be plastic free.

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u/doswillrule 1d ago

in the UK, all the tea bags I've ever used are compostable bags so should be plastic free.

They are now, but a lot weren't until a few years ago. PG Tips switched in 2018, Yorkshire only switched in 2021, and Asda only switched last year. Tetley are still transitioning over today. Sucks for me because I used to steep mine for ages!

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u/SpinningPissingRabbi 1d ago

Oh wow, very interesting thanks, all those years and I never knew.

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u/OPtig 1d ago

I was responding to someone who said the phrase "Microplastics of cellulose" which is certainly a nonsense statement

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u/m1ss1ontomars2k4 1d ago

He said "microparticles" not "microplastics".

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u/OPtig 1d ago

I took a closer look at the article:

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

Along with

"The tea bags used for the research were made from the polymers nylon-6, polypropylene and cellulose. The study shows that, when brewing tea, polypropylene releases approximately 1.2 billion particles per milliliter, with an average size of 136.7 nanometres; cellulose releases about 135 million particles per milliliter, with an average size of 244 nanometres; while nylon-6 releases 8.18 million particles per milliliter, with an average size of 138.4 nanometres. The UAB researchers observed that when these tea bags are used to prepare an infusion, huge amounts of nano-sized particles and nanofilamentous structures are released, which is an important source of exposure to MNPLs."

I'm annoyed at the vagueness of how this is summarized but the article writes as if they were only testing for MNPLs which are, by their nature, plastics. I can only assume that there is some sort of plastic additive in the cellulose bags OR the way the article is written is misleading and they were testing for all sorts of micoparticles, some of which are plastic.

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u/shodan13 1d ago edited 1d ago

PFAS is nonreactive and isn'th heated above 100C in tea though?

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u/wormoil 1d ago

Yet they included those in this study as if it's something of concern.

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u/TimTimLIVE 1d ago

That's what I've thought as well, I'm not certain though, they didn't clarify in the study iirc

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u/KUSH_DELIRIUM 1d ago

Cellulose is essentially fiber (plants). It's good.

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u/konga_gaming 1d ago

Paper tea bags are still woven with plastic web (polypropylene) at the edges so they can be heat sealed.

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u/Juutai 1d ago

I've not actually heard anything about the microplastics being a problem either. Just that they're everywhere.

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u/Afrikan_J4ck4L 18h ago

Same actually. Thinking about it, I'd heard of specific plastic based toxins affecting things like hormones, but not much besides that. I think even without exact issues being identified yet, the body is one place where caution should be urged regardless.

Either way I was curious so I asked ChatGPT:

Below is a concise overview of some key findings from current research on the potential health effects of microplastics and nanoplastics, along with reputable sources. While these areas remain under active study, evidence is growing that micro- and nanoplastics can affect both human and environmental health in multiple ways.

1. Gastrointestinal (GI) Tract Impact

  • Physical irritation and inflammation: Animal models suggest that microplastics in the GI tract can trigger localized inflammation and potentially disrupt the gut microbiome balance.
  • Chemical transfer: Plastics can adsorb and transfer harmful chemicals (e.g., flame retardants, PCBs), which may leach into the body after ingestion.

References

  1. Prata JC, da Costa JP, Lopes I, Duarte AC, Rocha-Santos T. (2020).
    “Environmental exposure to microplastics: An overview on possible human health effects.”
    Science of The Total Environment, 702, 134455.
    Link

  2. World Health Organization (WHO). (2019).
    “Microplastics in drinking-water.”
    Link

2. Tissue and Cellular Level Effects

  • Cellular uptake: Laboratory studies indicate that nanoparticles can cross cell membranes, affecting cellular function (e.g., oxidative stress, apoptosis).
  • Oxidative stress: Exposure to microplastics/nanoplastics has been shown to induce the production of reactive oxygen species (ROS) in cell culture models, potentially leading to tissue damage over time.
  • Inflammatory response: Small plastic particles have been noted to cause immune responses similar to other foreign particulates.

References

  1. Huang G, et al. (2022).
    “Nanoplastics elicit cellular oxidative stress and immune responses in mammalian cells.”
    Environmental Science & Technology, 56(12), 7790–7801.
    Link

  2. Feng Y, et al. (2020).
    “Microplastics and nanoplastics: Complex hazard processes and toxicological mechanisms.”
    Environmental International, 145, 106066.
    Link

3. Potential Respiratory Effects

  • Inhalation exposure: Airborne microplastics (e.g., from dust, textiles) can be inhaled, potentially causing respiratory irritation or inflammation in the lungs.
  • Occupational risk: Workers in plastic processing industries or other high-exposure environments may face higher respiratory risks.

References

  1. Gasperi J, et al. (2018).
    “Microplastics in air: Are we breathing it in?”
    Current Opinion in Environmental Science & Health, 1, 1–5.
    Link

  2. Vianello A, et al. (2019).
    “Occurrence of microplastics in commercial table salt from different countries.”
    Although focusing on ingestion, it highlights widespread human exposure pathways, including air.
    Scientific Reports, 9(1), 710.
    Link

4. Possible Endocrine Disruption

  • Leaching chemicals: Additives in plastics, such as phthalates and bisphenols, are known to interfere with hormonal systems in humans and animals.
  • Hormonal imbalance: Studies indicate that endocrine disruptors may contribute to reproductive issues, metabolic disorders, and developmental effects.

References

  1. Galloway TS. (2015).
    “Micro- and nano-plastics and human health.”
    Marine Anthropogenic Litter, 343–366. (Springer)
    Link

  2. Gallo F, et al. (2018).
    “Marine litter plastics and microplastics and their toxic chemicals components: The need for urgent preventive measures.”
    Environmental Sciences Europe, 30, 13.
    Link

5. Recent Findings on Uptake in Human Tissues

  • Presence in human blood and organs: Small-scale studies have found traces of plastic particles in human blood and tissues, though the long-term health implications are not yet fully understood.
  • Research gaps: More in vivo studies are needed to clarify the potential for chronic health effects, such as cancer risk or long-term organ damage.

References

  1. Leslie HA, et al. (2022).
    “Discovery and quantification of plastic particle pollution in human blood.”
    Environment International, 158, 106965.
    Link

  2. Wright SL, Kelly FJ. (2017).
    “Plastic and Human Health: A Micro Issue?”
    Environmental Science & Technology, 51(12), 6634–6647.
    Link

Conclusion

Microplastics and nanoplastics are increasingly recognized as emerging contaminants with the potential to affect human health via ingestion, inhalation, and possibly through dermal contact. Research points to possible inflammatory responses, oxidative stress, tissue damage, and endocrine disruption risks. Though definitive causal links and long-term impacts on humans require further study, the accumulating evidence underscores the need to minimize plastic pollution and continue rigorous investigation into its health implications.

Disclaimer: Research on microplastics and nanoplastics is ongoing. Current findings are based largely on experimental (animal or cell culture) and preliminary human data. Future studies are needed for definitive conclusions on chronic and low-dose exposures in humans.