The Contaminants of Microplastics in Infusion Tea Bags Sold in Thailand

Abstract

     The objective of this research is to investigate microplastic contamination in commercial tea bags available in Thailand, both before and after brewing. The findings aim to provide consumers with data for future purchasing decisions and to help elevate the safety standards of tea bag packaging in Thailand regarding microplastic (MP) levels. The research was conducted as a laboratory-based investigation. Samples of tea bags were collected from retail stores in Bangkok and online channels based on the market share of tea products in Thailand. Thirteen tea bag samples were selected, comprising five brands manufactured in Thailand and four imported brands. Fourier Transform Infrared Spectroscopy (FTIR) was employed to analyze the types of MPs present in the tea bags. Scanning Electron Microscopy (SEM) was used to quantify the number and measure the size of microplastic released from tea bags when immersed at room temperature and after brewing with 95°C hot water for 5 minutes.

     Results from FTIR analysis detected microplastic contamination in five tea bag samples, corresponding to 38.5% of the total samples. Microplastic  contamination was predominantly found in pyramid-shaped tea bags. SEM analysis revealed that the average number of MPs per tea bag was 1.27 million particles at room temperature, which increased by +113% to 2.72 million particles per tea bag after immersion in hot water, indicating that exposure to hot water significantly accelerated the release of microplastic from the tea bag material. Furthermore, the researcher calculated the number of microplastics per unit area of each tea bag to provide a more consistent standard unit of measurement for comparing microplastics (MPs) between tea bags of different sizes. They found that the number of MPs per square centimeter of each tea bag was 21,778 pieces/cm² at room temperature and increased by +123% to 48,552 pieces/cm² after steeping in hot water.