Hot Drinks in Paper Cups Release Billions of Nanoplastics Within 15 Minutes, Study Warns

A cup of iced coffee in a plastic cup may seem like the riskier choice compared to hot coffee in a paper cup. However, new research warns that pouring hot beverages into paper cups can release massive amounts of micro- and nanoplastics within just 15 minutes.

Researchers at the Indian Institute of Technology Kharagpur collected five types of disposable paper cups from the market, poured hot water at 85-90 degrees Celsius, and analyzed the liquid after leaving it for 15 minutes. The results were more alarming than expected. An average of 25,000 microplastic particles were detected per 100 milliliters, while nanoscale plastics—too small to see with the naked eye—numbered approximately 10.2 billion.

This means that drinking a single cup of coffee could introduce plastic particles into your body.

Paper on the Outside, Plastic on the Inside

The problem lies in the structure of paper cups. To prevent liquid from seeping through, the inside of paper cups is lined with a thin plastic coating. Infrared spectroscopy analysis by the research team confirmed that most paper cup coatings are made of high-density polyethylene (HDPE)—the same plastic commonly found in disposable packaging.

This coating layer becomes increasingly vulnerable when exposed to high-temperature liquids. Heat causes microscopic cracks to form, allowing plastic particles to break off into the beverage. During this process, not only microplastics but also chemical substances such as fluoride and sulfates, as well as some heavy metal components, were detected.

The concern is that these particles are extremely small. Microplastics and nanoplastics have a high potential for absorption into the body, and some are known to travel through blood vessels and reach deep into organs. Long-term exposure has raised concerns about potential disruption to immune function and hormonal systems.

The Misconception That Paper Cups Are Safer

Many people have considered paper cups a "safe alternative" to plastic cups. But the research results directly contradict this perception. Experiments reported by British media outlet The Independent also detected microplastics in both plastic cups and coated paper cups. While paper cups may be marginally better, they cannot be considered safe.

Particularly for those who drink two or three cups of hot coffee from paper cups daily, warnings suggest that the amount of nanoplastics consumed over a year could reach trillions of particles. The cumulative effect of "just one cup of coffee a day" is far from negligible.

Ways to Reduce Exposure in Daily Life

Experts recommend using reusable cups made of stainless steel, glass, or ceramic materials when drinking hot beverages. Simply using a personal tumbler can significantly reduce exposure.

If paper cups must be used, it helps to let boiling beverages cool slightly before pouring them in, or to drink the beverage as quickly as possible rather than letting it sit. While these are small habit changes, they can be meaningful in reducing repeated exposure.

The research team stated, "Paper cups look like paper, but they are actually plastic composites," adding that "there is a need for more systematic management of microplastic exposure from disposable food containers."

The study was published in the Journal of Hazardous Materials on Sunday.