Single-use paper cups used for takeaway coffee may release millions of plastic particles into hot beverages, according to a new study by researchers at the University of Queensland. The research found that paper cups lined with either conventional polyethylene (PE) or biodegradable polylactic acid (PLA) released micro- and nanoscale plastic particles when exposed to hot water, challenging the assumption that a cup made primarily from paper is necessarily plastic-free.
The findings are particularly notable because the biodegradable PLA-lined cups released substantially more particles than the conventional PE-lined cups in the experiments. Researchers measured approximately 4.3 million nanoparticles per milliliter from PLA-lined cups, compared with 2.7 million particles per milliliter from PE-lined cups. The study, published in ACS Food Science & Technology, does not establish that drinking from paper cups causes illness, but researchers say the results warrant greater scrutiny of food-contact materials and their particle-release behavior.
Paper Coffee Cups Can Release Millions Of Plastic Particles
The University of Queensland research examined disposable paper cups designed for hot beverages.
Researchers focused on two types of plastic lining:
- Polyethylene (PE), a fossil-based plastic
- Polylactic acid (PLA), a biodegradable plastic alternative
Both types released plastic particles when exposed to hot liquid.
However, the amount released differed significantly between the two materials.
Microplastic Findings At A Glance
| Indicator | PE-Lined Cups | PLA-Lined Cups |
|---|---|---|
| Lining material | Polyethylene | Polylactic acid |
| Material description | Fossil-based plastic | Biodegradable plastic |
| Nanoparticles measured | ~2.7 million/mL | ~4.3 million/mL |
| Relative particle release | Lower | ~12× higher by total particle mass |
| Intended use | Hot beverages | Hot beverages |
The researchers said the PLA-lined cups released approximately 12 times more total particle mass than PE-lined cups under their experimental conditions.
Why Do Paper Cups Have Plastic Linings?
A paper cup is generally not made entirely from paper.
Disposable cups used for coffee, tea and other hot drinks often contain a thin polymer coating on the inside.
The lining helps make the cup resistant to water and prevents the liquid from soaking through the paper.
Without that barrier, paper would rapidly absorb hot beverages and lose structural integrity.
How A Paper Cup Is Constructed
Hot coffee
│
▼
┌─────────────────────┐
│ Plastic lining │
├─────────────────────┤
│ Paper layer │
├─────────────────────┤
│ Outer coating/print │
└─────────────────────┘
The research highlights why describing such products simply as “paper cups” can be misleading from a materials perspective.
A cup may be predominantly paper while still placing a plastic surface directly against the beverage.
PLA “Biodegradable” Linings Released More Particles
One of the study’s most striking findings involved PLA.
Polylactic acid is often promoted as a more environmentally friendly alternative to conventional petroleum-derived plastics because it is biodegradable under suitable conditions.
However, the research found that PLA-lined cups released significantly more plastic particles than PE-lined cups in the experiments.
The researchers measured approximately 4.3 million nanoparticles per milliliter from PLA-lined cups, compared with around 2.7 million per milliliter from PE-lined cups.
PE Vs PLA
Particle concentration measured
PE lining
2.7 million/mL
████████████████████
PLA lining
4.3 million/mL
████████████████████████████████
The result does not mean that PLA is inherently unsafe.
Lead researcher Dr. Elvis Okoffo specifically cautioned that the findings should not be interpreted as proof that people need to stop using paper cups or that PLA itself is unsafe.
What Are Microplastics And Nanoplastics?
Microplastics are very small plastic particles, while nanoplastics are even smaller particles generally measured at the nanoscale.
The newly published study distinguishes between:
- Microplastics: particles larger than 1 micrometer
- Nanoplastics: particles approximately 10-1,000 nanometers
The extremely small size of nanoplastics makes them particularly difficult to detect and study.
Microplastic Size Comparison
| Particle | Approximate Scale |
|---|---|
| Microplastic | >1 micrometer |
| Nanoplastic | 10-1,000 nanometers |
| Human hair | Much thicker than these particles |
| Visible plastic fragment | Typically much larger |
Researchers said the nanoparticles detected in the experiments were around 1,000 times thinner than a human hair.
Hot Liquid Is The Key Exposure Condition
The study specifically examined what happens when paper cups come into contact with hot liquid.
The researchers’ experiments were designed to evaluate particle release under hot-water conditions.
This matters because temperature can affect the behavior and stability of polymer materials.
Previous research has also found that increasing temperature can increase microplastic release from several types of plastic products.
Heat And Plastic Particle Release
Hot beverage
│
▼
Higher temperature
│
▼
Greater stress on polymer lining
│
▼
Potential particle release
│
▼
Microplastics + nanoplastics
The precise amount released depends on factors including the material, surface characteristics, temperature and exposure conditions.
The Study Used Advanced Analytical Techniques
The researchers did not rely on a single detection method.
The published study used an integrated analytical workflow involving techniques including:
- Pyrolysis-gas chromatography-mass spectrometry
- Asymmetrical flow field-flow fractionation
- Multiangle light scattering
- Nanoparticle tracking analysis
- Electron microscopy
These methods were used to characterize and quantify particles released from the different cup linings.
Study Methodology
| Method | Purpose |
|---|---|
| Py-GC-MS | Polymer/material analysis |
| AF4-MALS | Particle separation and characterization |
| Nanoparticle tracking | Particle-size and concentration assessment |
| Electron microscopy | Visual examination |
| Integrated analysis | Cross-checking particle characteristics |
The combination was intended to provide a more detailed picture of both microplastic and nanoplastic release.
What The Researchers Actually Found
The central finding was not simply that paper cups contain plastic.
It was that plastic-lined paper cups can release measurable quantities of plastic particles when exposed to hot liquid.
Both PE and PLA linings showed particle release.
The PLA lining produced the higher release in the experimental comparison.
Main Findings
| Finding | Result |
|---|---|
| PE-lined cups released particles | Yes |
| PLA-lined cups released particles | Yes |
| PLA released more particles | Yes |
| PLA total particle mass vs PE | ~12× higher |
| Nanoparticles from PE | ~2.7 million/mL |
| Nanoparticles from PLA | ~4.3 million/mL |
| Health effects established by study | No |
The final point is particularly important when interpreting the headlines surrounding the research.
Does This Mean Drinking Takeaway Coffee Is Dangerous?
The study does not establish that drinking coffee from paper cups causes disease or other specific health problems.
Researchers are concerned about potential exposure, but the long-term health effects of ingesting microplastics and nanoplastics remain an active area of scientific research.
Dr. Okoffo said the findings add to evidence that plastic products used in food storage and preparation may represent an overlooked route of human exposure.
That is different from demonstrating that the particles released from a particular cup cause a specific health outcome.
What The Study Does And Does Not Show
| Question | Evidence From Study |
|---|---|
| Do paper cups contain plastic linings? | Yes, in the tested products |
| Can linings release particles? | Yes |
| Does hot liquid cause particle release? | Yes, under test conditions |
| Does PLA release more particles than PE? | Yes, in this experiment |
| Do humans ingest some released particles? | Potential exposure is the concern |
| Does the study prove disease? | No |
| Does it establish long-term health effects? | No |
This distinction is important for consumers and policymakers.
Researchers Want Better Food-Contact Safety Testing
The research team argues that food-contact materials should be evaluated not only for their environmental properties but also for how they behave during normal use.
This is particularly relevant for products that come into direct contact with hot beverages.
Researchers suggested that regulators could consider testing for micro- and nanoplastic release as part of safety assessments for food-contact products.
Proposed Areas For Greater Oversight
| Area | Potential Action |
|---|---|
| Material safety | Test plastic particle release |
| Hot-food applications | Evaluate heat exposure |
| Product labeling | Identify lining materials |
| Manufacturing | Develop lower-shedding coatings |
| Regulation | Establish particle-release standards |
| Consumer awareness | Explain packaging materials |
The researchers also called for manufacturers to explore linings that release fewer particles.
“Biodegradable” Does Not Automatically Mean Plastic-Free
The findings raise a broader issue around how consumers understand environmentally friendly packaging.
PLA is a biodegradable polymer, but it remains a plastic material.
Its environmental benefits and its behavior when exposed to hot beverages are separate questions.
A material can have advantages in one context while still requiring safety evaluation in another.
Environmental Vs Food-Safety Questions
| Question | What It Addresses |
|---|---|
| Is the material biodegradable? | Environmental breakdown |
| Is it recyclable? | Waste management |
| Does it shed particles? | Material behavior |
| Are released particles harmful? | Health risk |
| Does it meet food-contact standards? | Regulatory safety |
| What happens at high temperatures? | Use-condition safety |
The study highlights why these questions should not be treated as interchangeable.
Earlier Research Also Found Microplastic Release
The new research adds to an existing body of work examining plastic particle release from disposable cups.
A 2021 study published in Science of the Total Environment reported that hot water exposure to disposable paper cups caused microplastic release and the transfer of certain ions from cup linings. It estimated approximately 25,000 micron-sized microplastic particles in 100 mL of hot water after 15 minutes under its experimental conditions.
That study also identified sub-micron particles and detected elements including lead, chromium and cadmium in the examined lining materials.
The newer University of Queensland research uses different methods and focuses specifically on comparing PE and PLA-lined cups, so its numerical findings should not simply be combined with the earlier study.
Research Comparison
| Study | Main Focus | Key Finding |
|---|---|---|
| 2021 paper-cup study | Hot-water exposure | Microplastic release detected |
| 2026 UQ study | PE vs PLA linings | Both released particles |
| 2026 UQ result | PLA vs PE | PLA showed ~12× higher total particle mass |
| Broader research | Plastic containers | Heat can increase particle release |
Together, the studies point to the need for further standardized testing.
Indian Consumers May Face Similar Exposure Questions
Paper cups are widely used in India for tea, coffee and other takeaway beverages.
A 2025 review published in Discover Applied Sciences examined concerns surrounding microplastics from paper cups and tea bags, including research on plastic-lined paper cups used with hot beverages.
However, the new University of Queensland study was conducted by Australian researchers and should not be interpreted as a direct measurement of microplastic exposure from cups sold in India.
Different manufacturers can use different paper, coating materials, thicknesses and production processes.
Why Cup Design Matters
Manufacturer
│
▼
Lining material
│
▼
Coating thickness
│
▼
Surface properties
│
▼
Temperature exposure
│
▼
Particle-release behavior
Consumers therefore cannot assume that every paper cup releases the same amount of plastic.
Reusable Cups Could Reduce Single-Use Packaging
The research does not recommend that consumers completely stop drinking takeaway beverages.
However, people seeking to reduce exposure to single-use packaging can consider reusable alternatives made from materials such as glass, ceramic or stainless steel.
The choice also has environmental implications because reusable products can reduce the volume of disposable cups entering waste streams when used repeatedly.
Cup Options
| Cup Type | Main Material | Single-Use? | Plastic Contact With Drink |
|---|---|---|---|
| Paper cup | Paper + polymer lining | Usually | Often |
| PLA-lined paper cup | Paper + PLA | Usually | Yes |
| Plastic cup | Polymer | Usually | Yes |
| Glass cup | Glass | Usually reusable | No polymer lining needed |
| Ceramic cup | Ceramic | Usually reusable | No polymer lining needed |
| Stainless steel | Metal | Usually reusable | No polymer lining needed |
The choice involves trade-offs around convenience, cost, cleaning and environmental impact.
Manufacturers Could Face New Pressure
The findings could increase scrutiny of disposable cup manufacturers.
If regulators begin requiring standardized microplastic and nanoplastic testing, producers may need to provide more information about their lining materials and particle-release performance.
Manufacturers could also face pressure to develop coatings that maintain waterproofing while reducing particle shedding.
Potential Industry Changes
Research findings
│
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Consumer awareness
│
▼
Regulatory scrutiny
│
▼
Testing requirements
│
▼
New lining technologies
│
▼
Lower particle release
Such changes could eventually influence the design of cups, food containers and other products that combine paper with plastic coatings.
The Bigger Picture
The University of Queensland study adds to growing scientific evidence that disposable paper cups are not necessarily plastic-free and that their linings can release micro- and nanoscale particles into hot liquids. The research found approximately 4.3 million nanoparticles per milliliter from PLA-lined cups and 2.7 million per milliliter from PE-lined cups, while total particle mass from PLA was about 12 times higher in the experiments.
The findings should be interpreted carefully. The study does not prove that drinking takeaway coffee from paper cups causes illness, nor does it establish the long-term health effects of ingesting the detected particles. Instead, it highlights a potential exposure pathway and argues that food-contact materials should be evaluated for particle release under realistic conditions of use. Earlier research has also detected microplastic release from paper cups exposed to hot water, suggesting that the issue warrants continued investigation.
Looking Ahead
The next step for researchers and regulators will be determining how much of the material released in laboratory experiments actually reaches beverages under real-world conditions and what happens after ingestion. Standardized testing could make it easier to compare different cup designs, temperatures, lining materials and manufacturers. Such work will be particularly important as biodegradable polymers such as PLA become more common in food packaging.
For consumers, the study is best viewed as a reason to understand what is inside supposedly paper-based food containers rather than as evidence that an occasional takeaway coffee is inherently dangerous. Reusable glass, ceramic or stainless-steel cups can reduce reliance on single-use packaging, while manufacturers and regulators can work toward clearer labeling and stronger testing of materials intended for hot food and beverages.
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