Takeaway Coffee Cups Shed Millions of Microplastic Particles, Study Finds

Single-use paper cups used for takeaway coffee, tea and other hot drinks release millions of microplastic particles when they meet hot liquid, according to researchers at the University of Queensland's Queensland Alliance for Environmental Health Sciences. The team, led by Dr. Elvis Okoffo, tested cups lined with either fossil-based polyethylene (PE) or the biodegradable alternative polylactic acid (PLA), both used to make paper cups water-resistant. The findings are published in ACS Food Science & Technology.

Okoffo said a cup made mostly of paper is not necessarily plastic-free, because many carry a thin plastic lining for water resistance and structural strength. The study found that PLA-lined cups released a total particle mass roughly 12 times higher than PE-lined cups. Measured concentrations were about 4.3 million nanoparticles per millilitre from PLA-lined cups, compared with 2.7 million particles per millilitre from PE-lined cups; the nanoparticles are around a thousand times thinner than a human hair.

Okoffo said the impact of plastic particles on human health remains unclear, and the study does not mean people should stop using paper cups or that PLA is inherently unsafe. He said the chemicals used in plastics are not meant to be consumed, and called the findings evidence that new plastic products used for food storage and preparation are an often-overlooked source of human exposure to plastic through ingestion.

Okoffo said policymakers and regulators could consider testing for micro- and nanoplastic release as part of safety assessments for food-contact materials, particularly products meant for hot beverages, and that manufacturers could develop cup linings that shed fewer particles when exposed to hot liquid.