Disposable tea bags have proven to be one of the main sources of polymer microparticles, countless of which end up in the oceans every year along with wastewater. Canadian scientists write about this in the journal Environmental Science & Technology.
“When you brew a tea bag, about 11.6 billion plastic microparticles and another three billion polymer nanoparticles are added to the boiling water. This is several orders of magnitude more than it was possible to find in other types of food and drinks, including in plastic water bottles,”the scientists write.
Polymer oceans
Each year, approximately 300 million tons of plastic waste is discharged into wastewater and landfills, most of which cannot be decomposed by soil microbes. As a result, it remains almost intact for tens and even hundreds of years. When this debris enters the oceans, it bumps into huge heaps, similar to the so-called “big debris patch” in the Pacific Ocean.
Therefore, ecologists and oceanologists often jokingly call the last half century the "plastic period" because of the huge amount of micro-fragments of polymers in the waters of the World Ocean. As the observations of scientists show, these particles do not stay in the water for a long time, most likely, they are eaten by marine organisms. A person, as Canadian researchers found a year ago, every year, on average, swallows about 40-60 thousand microparticles of plastic.
Laura Hernandez and her colleagues at McGill University in Montreal (Canada) have discovered another source of plastic microparticles that can potentially have a significant impact on human health. To do this, they studied what happens to ordinary tea bags when immersed in boiling water.
Manufacturers of many brands of tea use plastic bags made of microscopic nylon threads rather than paper ones. In addition, they contain PVC and polypropylene. After several recent scandals, environmentalists have become interested in how safe such structures are for human and animal health.
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Plastic tea leaves
Erdnandez and her colleagues purchased several bags of four different types of fruit teas popular in Canada, removed the tea leaves and boiled them for five minutes. After that, the scientists filtered the water, extracted the nanoparticles from it and studied the structure of the plastic bags themselves using an electron microscope.
The results of these measurements exceeded all the expectations of scientists - billions of micro- and nanoparticles of plastic of various sizes floated in the water. When environmentalists studied their chemical composition and photographs of the sachets, they came to the conclusion that initially these nanoparticles were not in the tea, they appeared already during the brewing process. This is supported by the fact that their shape and other characteristics depended on the material and structure of the bags themselves.
Having discovered this phenomenon, scientists tested what would happen if these nanoparticles were introduced into a nutrient medium where daphnia crustaceans lived. These experiments showed that their appearance caused some disturbances in the development and behavior of these invertebrates, and the severity of these problems grew along with the concentration of plastic in the water.
On the other hand, according to scientists, they do not yet have an accurate understanding of how "tea" microplastics affects human health in the long term. In the near future, they plan to get an answer to this question, as well as reveal the very mechanism of how nanoparticles are formed when a sachet enters boiling water.