From your morning tea to a cold soft drink, UK beverages carry hidden microplastic loads, and hot drinks could be giving you an even bigger dose.
Study: Synthetic microplastics in hot and cold beverages from the UK market: Comprehensive assessment of human exposure via total beverage intake. Image Credit: SAG stock / Shutterstock
In a recent article published in the journal Science of the Total Environment, researchers assessed the levels of microplastics (MPs) that people are exposed to through their daily intake of fluids using survey data and laboratory analysis in the UK.
They detected MPs in all the beverages that people reported consuming and noted higher concentrations in hot drinks like tea, probably due to leaching from plastic packaging induced by heat, with average concentrations expressed in MPs per litre also reported for direct comparison.
Background
MPs, defined as synthetic particles between 1 μm and five mm in size, are persistent environmental contaminants found in marine, freshwater, terrestrial, and atmospheric environments. In practice, this study’s detection threshold was >10 μm due to μ-FTIR analytical limits. They can carry toxic chemicals, enter the food chain, and pose potential risks to human health.
Human exposure occurs through food, water, air, and consumer products, but drinking water studies dominate the research, showing variable MP concentrations across countries. Evidence also shows MPs in beverages like beer, tea, coffee, and soft drinks, with possible sources including the water used, packaging materials, manufacturing processes, and preparation methods.
While some studies report MPs in individual beverage types, no comprehensive assessment exists for a broad range of hot and cold beverages from one country. Furthermore, most exposure estimates consider only water intake, overlooking the role of other drinks in total fluid consumption.
Given that beverage choices vary socially and culturally, excluding them may underestimate exposure. Researchers addressed this gap by establishing baseline MPs data for widely consumed UK beverages, surveying daily beverage intake among UK adults, and combining this data to estimate MPs exposure from total fluid intake to provide a more realistic assessment essential for evaluating potential health risks.
About the Study
In this study, researchers analyzed MPs in 155 samples comprising 5 samples from 31 beverage types from popular UK brands, collected from supermarkets and coffee shops in 2024. Beverages included hot and iced coffee, hot and iced tea, juices, energy drinks, and soft drinks.
Samples were processed in a clean room under strict contamination controls. Cold drinks were filtered immediately, while hot drinks were cooled for 30 minutes before filtration. MPs were extracted by vacuum filtration through 0.45 μm silver membrane filters, followed by digestion of organic matter using hydrogen peroxide at 60 °C for 24 hours.
Analysis was performed using spectroscopy methods to identify polymer types and particle characteristics with a 70% or more spectral match. Shapes, sizes, and counts were determined via microscope imaging.
An online survey of 201 adults recorded daily beverage intake, which was combined with MPs concentration data (expressed in MPs/L in the primary results and in MPs/cup for product-specific discussion) from this study and previous UK water studies to estimate exposure in MPs/kg body weight/day. Quality control included blank samples and recovery tests. Statistical analyses assessed differences between beverage types.
Key Findings
MPs were detected in all 155 beverage samples analyzed. In MPs/L terms, hot coffee averaged 43 ± 14 MPs/L, iced coffee 37 ± 6 MPs/L, hot tea 60 ± 21 MPs/L, iced tea 31 ± 7 MPs/L, fruit juice 30 ± 11 MPs/L, energy drinks 25 ± 11 MPs/L, and soft drinks 17 ± 4 MPs/L.
For product-specific serving comparisons, hot coffee in disposable paper cups averaged 16 MPs/cup, much lower than some previous studies, as they excluded cellulose-based particles and focused only on synthetic polymers thicker than 10 μm. Coffee in glass cups had fewer MPs, while older coffee machines released more MPs, likely from material degradation. Iced coffee in cups made of polyethylene terephthalate (PET) averaged 11 MPs/cup, mostly PET, with possible contributions from ice. Ice used in iced coffee has previously been identified as a potential MP source. Hot coffee contained significantly more MPs than iced coffee.
Hot tea in paper cups averaged 22 MPs/cup, higher than tea in glass cups (14 MPs/cup). The most expensive tea bags had the highest MP counts, averaging 27 ± 3 MPs/cup. Iced tea in PET bottles had fewer MPs than hot tea, reinforcing heat’s role in MP release.
Fruit juice in PET bottles had higher MP levels (42 ± 4 MPs/L) than carton packs (23 ± 3 MPs/L). Energy drinks in plastic packaging contained more MPs (40 ± 7 MPs/L) than canned versions (18 ± 3 MPs/L). Soft drinks in plastic bottles averaged 17 ± 4 MPs/L, in line with international studies.
Particle sizes ranged mostly from 10–200 μm, with iced tea having the smallest particles and hot tea the largest. Across all beverages, fragments dominated (72–93%) over fibres. Polymer types matched packaging materials, with polypropylene (PP) the most abundant overall, followed by polystyrene (PS), polyethylene terephthalate (PET), and polyethylene (PE). Detection of polyamide (PA) and polylactic acid (PLA) in some tea and coffee sachets was linked to intentional inclusion for texture. This confirmed packaging as a major MP source, with additional contributions from production processes, air, and water, including atmospheric deposition and wear from plastic machinery parts.
Conclusions
In this study, researchers revealed widespread MP contamination across popular UK beverages, with higher levels in hot drinks, underscoring the role of temperature in accelerating MP release from packaging.
Polymer composition largely reflected packaging materials, but secondary sources, such as contaminated water, atmospheric fallout, and production equipment, also contribute. Estimated daily intakes from all beverages were 1.7 MPs/kg body weight/day for females and 1.6 MPs/kg body weight/day for males, exceeding UK drinking-water-only estimates, suggesting that water-based exposure assessments underestimate true intake.
Strengths include a large sample size across multiple brands, focus on synthetic polymers, and polymer-type identification. The inclusion of a local consumption survey allowed estimation of real-world exposure.
Limitations involve the use of regional consumption data rather than national statistics, potential market representation gaps, and a detection limit excluding MPs less than 10 μm. This size restriction may underestimate the total MP burden.
Overall, the findings provide robust evidence that beverage consumption contributes significantly to microplastic ingestion. The research team highlighted the need for more comprehensive monitoring, improved packaging materials, and public awareness, in line with the discussion in the paper.
