evidence: But are you aware that some tea bags contain plastic? Several tea bag brands use polypropylene, a sealing plastic, to keep their tea bags from falling apart. This plastic is not recyclable or biodegradable. [...] And that's not the only problem, research from McGill University in Canada also found that some types of tea bag leak millions of plastic particles into our drinks not only from the sealing plastic but from the bag itself. [...] The scientists found that one plastic tea bag releases around 11.6 billion microplastics and 3.1 billion smaller nanoplastic particles into the cup. Those, in turn, end up in the drinker's digestive system. The findings were published in the Journal of Environmental Science & Technology.