By Lois Zoppi, BA
Reviewed by Kate Anderton, B.Sc. (Editor)

The war on plastic is gaining traction worldwide, and a huge number of households are trying to reduce their reliance on plastic. A recent YouGov poll showed that the areas in which people in the UK are trying to reduce their plastic consumption include fresh fruit and vegetables (81 percent), household and cleaning products (36 percent), homeware (32 percent) and personal care products like toothpaste and shampoos (27 percent).

This poll on UK shopping habits also found that more than half of the survey respondents were happy to pay more for eco-friendly packaging, so why are tea companies opting to use plastic teabags over eco-friendly options?

A plastic polymer has to be used in order for the teabags to stay sealed and keep their shape in hot water, tea manufacturers claim, also saying that non-plastic teabags would be too expensive to make.

This is despite evidence showing that the type of plastic used in teabags (polypropylene) can cause damage to the endocrine system, fertility, and increase a person’s chances of developing genetic mutations and tumors.

Researchers have published a study in the American Chemical Society’s journalEnvironmental Science and Technology that reveals plastic tea bags release “billions” of plastic micro- and nanoparticles into the tea, which are then consumed by the millions of tea-drinkers worldwide (with 159 million tea-drinkers in America alone).

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The authors write:

The increasing presence of micro- and nano-sized plastics in the environment and food chain is of growing concern. Although mindful consumers are promoting the reduction of single use-plastics, some manufacturers are creating new plastic packaging to replace traditional paper uses, such as plastic teabags.”

The researchers express concern over the safety of these new plastic teabags, explaining that water is often at or above 95 °C when teabags are in the water, and the risk of plastics degrading or releasing toxic substances increases when the water is hotter than 40 °C.

Researcher Nathalie Tufenkji and her colleagues aimed to determine whether plastic teabags release micro- and nanoparticles into the drink in this new study.

Additionally, they explored the effect the micro- and nanoparticles had on aquatic creatures called Daphnia magna, commonly known as water fleas, which are often used in environmental investigations.

For their experiments, the researchers emptied the plastic teabags, washed them, and heated them in water to mimic normal brewing conditions. Utilizing electron microscopy, the researchers were able to confirm that one plastic teabag released approximately 11.6 billion microplastic particles and 3.1 billion nanoplastic particles when at brewing temperature.

The research team also found that the water fleas experienced anatomical and behavioral abnormalities when exposed to the micro- and nanoparticles.

While the aquatic organisms are not a direct indicator of how plastic ingestion could affect humans, the researchers state that the “high correlation between the acute toxicity of chemicals to [water fleas] and the corresponding toxicity values for mice and humans have been confirmed”.

They also say that the “predictive screening potential of aquatic invertebrate tests for acute oral toxicity in humans is better than that of the [rat test] for some chemicals.”

Plastic is a widespread problem

Unfortunately, it isn’t only teabags that are suffering from a plastic contamination problem. The study describes the wide range of foods that are affected by plastic contamination, highlighting what a widespread problem it is.

“Microplastics identified as poly(ethylene) and poly(ethylene terephthalate) were detected in table salt, at levels up to 681 particles/kg,” the authors write. “Several studies report the presence of microplastics in fish […] Others have shown that mussels can contain between 0.3 and 0.5 microplastics/g (wet weight) at the time of consumption.”

According to the study, the annual consumption of microplastics can range from 39,000 to 52,000 particles depending on sex and age. However, the study states that ultimately, the effect of micro- and nanoplastics on humans cannot yet be predicted due to a paucity of research on the subject.

The authors conclude:

Overall, the knowledge on adverse effects of plastic particles on human health is still lacking and there is an urgent need to investigate potential toxic mechanisms in higher vertebrates and humans, which is of vital importance when assessing the human health risk of micro- and nanoplastics.”

Journal reference:

Hernandez, L. M., et al. (2019). Plastic Teabags Release Billions of Microparticles and Nanoparticles into Tea. Environ. Sci. Technol. https://pubs.acs.org/doi/abs/10.1021/acs.est.9b02540