Drinks packaged in glass bottles may not be as pristine as consumers believe. A new study by France’s food safety agency, ANSES, reveals that beverages sold in glass bottles – including water, soda, beer and wine – contain significantly higher levels of microplastics than those packaged in plastic bottles or metal cans.
On average, researchers found around 100 microplastic particles per litre in glass-bottled soft drinks, lemonade, iced tea, and beer – a level five to fifty times higher than detected in plastic bottles. For water, contamination was lower overall, with 4.5 particles per litre in glass bottles compared to 1.6 in plastic.
“We expected the opposite result,” said Iseline Chaib, a PhD student who led the research. “But we noticed that in glass, the particles emerging from the samples were the same shape, colour and polymer composition as the paint on the outside of the caps that seal the glass bottles.”
The paint used on the metal caps showed microscopic scratches, likely caused by friction between caps during storage. ANSES noted that these scratches can release plastic particles onto the surface of the caps, which then contaminate beverages when opened.
Wine, however, was a surprising exception: even glass bottles with caps contained few microplastics, though the reason for this discrepancy “remains to be explained,” said Guillaume Duflos, research director at ANSES.
Although no direct evidence yet links microplastic ingestion to human health risks, scientists are increasingly concerned about their spread in food and beverages. ANSES highlighted that drink manufacturers could mitigate the issue by adopting simple cleaning measures. The agency tested a method of blowing the caps with air and rinsing them with water and alcohol, which reduced microplastic contamination by 60 percent.
The findings were published in the Journal of Food Composition and Analysis and form part of ANSES’s ongoing effort to monitor microplastic exposure.
