Posh pyramid tea bags could be leaving behind billions of microscopic plastic particles in cups, new research has revealed.
A Canadian study of four different commercial teas using plastic mesh, to help tea leaves infuse better, found a single bag released about 11.6bn of microplastic and 3.1bn smaller nanoplastic particles into the hot water during the brewing process.
Microplastics are defined as any plastic debris less than five millimetres in length and commonly found in tap and bottled water, as well as some foods.
The World Health Organisation said microplastics in water do not appear to pose a health risk, although called on more research to gain information on the wider environmental impact.
A plastic seal is used in popular paper pyramid bags to help retain their shape for a better brew when hot water is applied.
During the test, researchers at McGill University in Montreal removed the tea and placed the empty teabags in water heated to 95C (203F), as if brewing tea.
Although invisible to the naked eye, the level of microplastics found were significantly higher than plastic loads previously reported in other foods during similar studies.
Researchers did not reveal the names of the brands tested, but advised consumers to choose loose teas sold without packaging to reduce the amount of plastic ingested.
WHO said most water supplies will contain traces of microplastics, but 90 per cent can be removed with effective waste water treatment procedures.
In its first report on microplastics in water supplies, the United Nations health body said larger particles, and most smaller ones, pass through the body without being absorbed.
Miniscule elements of polymers have also been found in bottled water, with scientists concluding they have been deposited by screw-on plastic caps.
