Contrary to long-held beliefs about glass being a safer packaging option, a new study by France’s food safety agency ANSES has revealed that drinks sold in glass bottles contain far more microplastics than those in plastic or metal containers. The study found that beverages such as beer, soda, and iced tea in glass packaging contained up to 100 microplastic particles per litre nearly 50 times higher than in plastic bottles.
Published in the Journal of Food Composition and Analysis, the study traced the unexpected source of contamination to the paint on metal caps used to seal glass bottles. According to lead researcher Iseline Chaib, particles isolated from the drinks matched the shape, colour, and polymer composition of the cap paint, indicating they likely flaked off during sealing.
Among the tested beverages, beer bottles showed the highest contamination averaging 60 particles per litre followed by lemonade. By contrast, water showed the least microplastic content, with glass-bottled water containing 4.5 particles per litre compared to only 1.6 in plastic-bottled water.
Interestingly, wine bottles were the exception, as they are typically sealed with corks rather than painted caps, resulting in lower microplastic levels.
The ANSES team also tested a cleaning solution blowing and rinsing caps with a water-ethanol-water cycle which successfully reduced microplastic contamination by nearly threefold.
The study comes amid growing concern over microplastic pollution, which has reached every corner of the planet from the deepest ocean trenches to human bodies, including the brain and placenta. With plastic production skyrocketing from 1.5 million tonnes in the 1950s to over 400 million tonnes in 2022, experts warn that microplastics are now an unavoidable part of modern ecosystems.
This new research suggests that packaging material alone doesn’t guarantee safety from microplastic exposure and urges manufacturers to rethink sealing and handling processes for glass-bottled drinks.