"These findings underscore the importance of identifying new environmentally relevant micro- and nanoplastic exposure sources, for developing realistic samples, and further investigating their potential human health effects," researchers stated it the study.
The researchers tested three types of tea bags: nylon, polypropylene, and cellulose. They used advanced methods to copy the tea-making process and check the water for plastic particles.
The study found that different types of plastic released different amounts of particles. Polypropylene tea bags released the most, with 1.20 billion particles per milliliter. Nylon bags released the least, with 8.18 million particles per milliliter.
"Recent investigations have elucidated that teabags significantly contribute to the release of millions of micro- and nanoplastics, adding to their daily ingestion by humans," the researchers wrote in their paper.
To see how these particles might affect the body, the team exposed three types of human gut cells to the plastic particles. They found that all three types of plastic could interact with the cells' nuclei after 24 hours.
"This may suggest that cell internalization and intracellular trafficking rates are cell type dependent," the researchers noted.
Importantly, the study found that gut cells that make mucus (HT29-MTX) took in the most plastic particles. This suggests that the mucus layer, which usually protects the gut, might actually help absorb plastic contaminants.
"These differences can result in specific accumulation patterns, toxicity profiles, immune responses, and long-term health effects such as genotoxicity and carcinogenicity," the researchers warned.
The study’s findings raise concerns about the widespread use of plastic in food and drink packaging, with tea bags just one example.
The team stressed the need for more research to understand real-world exposure to the particles and to develop standard methods for measuring their release and toxic effects.
"Our study sheds light on understanding these relationships, which are crucial for assessing the environmental and health risks associated with real-world micro- and nanoplastic ingestion," the researchers stated.
As people become more aware of plastic pollution, this study adds to the growing understanding that the problem goes beyond what can be visibly seen, as microscopic particles also carry hidden health risks.