Synthetic microplastics in hot and cold beverages from the UK market: Comprehensive assessment of human exposure via total beverage intake

Although few studies have assessed human exposure to microplastics (MPs) via drinking, almost all have considered human daily fluid intake as composed solely of water. This study aims to comprehensively assess human exposure to MPs via total fluid intake, including beverages (hot and/or cold), as well as water (tap and/or bottled). To achieve this aim, we used a tiered approach that combined laboratory analysis to quantify synthetic microplastics in 155 cold and hot common beverages sold on the UK market, with a public online survey to assess the average consumption of these beverages on a daily basis. MPs were detected in all analysed samples. The average concentration in hot coffee was 43 ± 14 MPs/l (n = 45, 1 standard deviation (SD)), while iced coffee averaged 37 ± 6 MPs/l (n = 10, 1SD). Notably, hot tea demonstrated the highest abundance of microplastics, with an average of 60 ± 21 MPs/l (n = 30, 1SD), compared to iced tea which had 31 ± 7 MPs/l (n = 10, 1 SD). Hot beverages had higher concentrations of MPs than cold beverages (P < 0.05), indicating the role of temperature in enhancing MPs leaching from packaging material to the beverage. Juices contained an average of 30 ± 11 MPs/l (n = 20, 1SD), and energy drinks averaged 25 ± 11 MPs/l (n = 25, 1SD). In contrast, soft drinks exhibited the lowest concentration, with an average 17 ± 4 MPs/l (n = 15, 1SD). The detected MPs in all beverages ranged in size from 10 to 157 μm. Fragments were the most abundant shape followed by fibres. Polypropylene (PP) was the most abundant polymer type followed by Polystyrene (PS), Polyethylene terephthalate (PET) and Polyethylene (PE). Plastic packaging materials (e.g., PET, PP, PE and PS) contributed substantially to the measured MPs contamination in respective beverages. Estimated daily average exposure from all beverages was calculated at 1.7 MPs/kg body weight/day for females and 1.6 MPs/kg body weight/day for males, which is higher than estimated microplastic exposure via drinking water only (1 MPs/Kg body weight/day). These findings underscore the potential risk associated with MPs contamination in daily beverages. Continued exposure to MPs through commonly consumed beverages may contribute substantially to daily intakes of MPs, leading to potential adverse implications for human health.