The study, lead by Dr Nathalie Tufenkji, tested four kinds of plastic tea bags in boiling water, and found that a single bag would release more than 11 billion microplastic and 3 billion nanoplastic particles. According to the reporting, “The tea bags examined in the McGill study were made of PET plastic or nylon. Often such tea bags are triangular in shape and allow the tea drinker to see the leaves through the bag.”