Paper cups are often seen as a sustainable alternative to plastic, but most people don’t realize they actually contain plastic. A thin inner lining (usually polyethylene) is added to prevent leaks. And when hot drinks are poured in, this lining can release microplastics directly into your beverage.
What Happens Inside the Cup?
When hot liquid (around 85–90°C) comes into contact with the plastic lining, the material begins to break down. Within minutes, microscopic plastic fragments detach and mix into the drink.
Research shows that this process happens quickly, even under normal drinking conditions.
How Many Microplastics Are Released?
Several scientific studies have tried to measure this:
- A commonly cited study found that around 25,000 microplastic particles can be released into 100 ml of hot liquid within 15 minutes
- That means a typical takeaway coffee (often 200–300 ml) could contain 50,000–75,000 particles
- Drinking three cups per day could lead to ~75,000 particles daily
Some newer research suggests even higher numbers when including smaller particles (sub-micron or nanoplastics), which are harder to detect but may exist in the millions per liter
Why Does This Happen?
Other paper cups are not purely paper—they are a composite material:
- Outer layer: paper (structure)
- Inner layer: plastic (waterproofing)
When exposed to heat:
- The plastic softens and degrades slightly
- The surface develops cracks and roughness
- Tiny fragments break off into the liquid
This happens even if the cup looks completely normal.
It’s Not Just Microplastics
Studies also show that other substances can leach into drinks:
- Heavy metals (e.g. chromium, cadmium, lead)
- Ions like fluoride, chloride, sulfate
- Chemical additives such as phthalates
These compounds originate from the plastic lining and manufacturing process.
The Bigger Picture
Paper cups are often marketed as eco-friendly, but:
- They are difficult to recycle due to the plastic lining
- They contribute to both environmental pollution and human exposure
Sources
- Study on microplastic release from paper cups (IIT Kharagpur) – Journal of Hazardous Materials / reported findings
- Health & Me summary of research on paper cups and microplastics
- Science Reporter (NIScPR) – experimental findings on microplastic release
- ScienceDirect – microplastics and chemical leaching from disposable cups
- Springer review on microplastics in paper cups and tea bags
- Overview of microplastics and exposure pathways
