Investigating the release of microplastics from tea bags into tea drinks and human exposure assessment

Background: The escalating production and utilization of plastics, driven by their distinctive properties, have significantly contributed to environmental pollution. One of these pollutants is microplastic (MP), which is present in many food products, such as tea bags. The primary objective of this study was to investigate the presence and characteristics of MPs in tea bags from five different brands in Iran. Methods: For this study, 30 tea bags from five different brands in Iran were selected for sampling. The unaltered tea bags (with tea) were placed in 100 mL of ultrapure water at a temperature of 95 °C for 5 minutes, representing an alternative approach involving tea bag sampling with tea and without rinsing. Subsequently, the samples were subjected to quantitative analysis using a scanning electron microscope (SEM) and qualitative analysis using a micro-Raman spectrometer. Results: All brands exhibited MP contamination, with an average abundance of 518 459 items per individual tea bag. Fibers were the predominant form of MPs, primarily falling within the 10–50 μm size range. Polymer analysis identified cellulose acetate (CA), nylon, polyethylene terephthalate (PET), and polyethylene (PE) as the prevalent types, with CA and nylon as the most frequent ones. The estimated daily intake (EDI) of MPs was calculated at approximately 17,282 items/kg-BW/day for children consuming 100 ml of tea daily and 14,813 items/kg-BW/day for adults consuming 400 mL of tea daily. Conclusion: This study underscores tea bag consumption as a significant route of MP exposure for humans and the environment, posing potential risks and implications.