Plastic tea bags release microscopic particles in tea

Many people are trying to reduce their consumption of plastic, but some tea manufacturers are going in the opposite direction: replacing traditional paper tea bags with plastic bags. Now the researchers reporting in ACS Environmental Science and Technology discovered that a soothing cup of the prepared beverage could be accompanied by a dose of micrometer and nanometer plastic from the sachets. The possible effects of ingestion of these particles on health are currently unknown, say the researchers.

Over time, plastic breaks down into tiny microplastics and even smaller nanoplastics smaller than 100 nanometers (nm) in size. (For comparison, a human hair has a diameter of about 75,000 nm.) Scientists have detected microscopic particles present in the environment, aquatic organisms and food sources, but they do not know not yet if they are harmful to humans.

Nathalie Tufenkji and her colleagues wondered whether newly introduced plastic tea bags could release micro- and nanoplastics into the drink while making coffee. They also wanted to explore the effects of released particles on small aquatic organisms called Daphnia magna, or water chips, which are model organisms often used in environmental studies.

To conduct their analysis, the researchers purchased four different commercial teas packed in plastic tea bags. The researchers opened the bags, removed the tea leaves and washed the empty bags. Then they heated the tea bags in water containers to simulate the infusion conditions.

Using electron microscopy, the team discovered that a single plastic tea bag at brewing temperature released about 11.6 billion microplastic particles and 3.1 billion nanoplastics in the water.

These levels were thousands of times higher than those previously reported in other foods. In another experiment, the researchers treated the water chips with different doses of micro and nanoplastics from tea bags. Although the animals survived, they had some anatomical and behavioral abnormalities.

The researchers say more research is needed to determine if plastics could have more subtle or chronic effects on humans.