Think your paper coffee cup is plastic-free? Study says think again

Your takeaway coffee may look like a paper product, but the cup holding it can contain a plastic lining that comes into contact with the hot drink.

Researchers from the University of Queensland have found that single-use paper cups can release millions of microplastic and nanoplastic particles when exposed to hot liquids. The study examined cups lined with fossil-based polyethylene (PE) and those using polylactic acid (PLA), a biodegradable plastic.

Biodegradable lining released more particles

The researchers found that both types of cups released plastic particles, but the amount varied significantly.

Dr Elvis Okoffo said PLA-lined cups released about 12 times more particle mass than PE-lined cups in the experiments.

"Single-use paper cups are used every day by millions of people around the world for coffee, tea and other hot beverages,'' Dr Okoffo told NDTV.

He explained that the paper component does not necessarily mean the cup is free of plastic.

"A cup made mostly of paper does not mean that the cup is plastic-free because many contain a thin plastic lining that provides water resistance and structural integrity."

The study, cited by NDTV, measured approximately 4.3 million nanoparticles per millilitre from PLA-lined cups, compared with 2.7 million particles per millilitre from PE-lined cups. The particles measured around a thousand times thinner than a human hair.

Researchers call for closer safety assessment

The findings add to concerns about exposure to micro and nanoplastics through everyday food-contact products. However, Okoffo cautioned against interpreting the study as a reason to stop using paper cups or declaring PLA unsafe.

"This does not mean that people should necessarily stop using paper cups, or that PLA is inherently unsafe,'' he said.

Instead, he said materials used for food and drink containers should be assessed for how many particles they release during normal use, alongside their environmental impact.

Better labelling and cup design urged

Per the NDTV report, the researchers called for greater transparency about the materials used in cup linings and suggested that regulators consider safety guidelines or warning labels.

"Policymakers and regulators could consider whether testing for micro- and nanoplastic release should form part of the safety assessment of food-contact materials, particularly products designed for hot beverages,'' he said.

Okoffo also suggested that manufacturers develop linings that release fewer plastic particles when exposed to hot liquids.