Microplastic pollution higher in glass-bottled drinks, paint on metal caps blamed

The study concludes with a counterintuitive result: beverages (beer, soda, iced tea, wine, or water) sold in glass bottles contain more microplastics than those sold in plastic bottles. Contamination is likely due to the paint that covers the metal caps, reveals a study released by the French Agency for Food, Environmental, and Occupational Health and Safety (ANSES) on Friday, June 20.

Conducted as part of a thesis funded by Anses and the Hauts-de-France region, this work was published in mid-May in the specialist journal Journal of Food Composition and Analysis .

The aim of this project was to "research the quantity of microplastics in several types of drinks sold in France and to examine the impact that different containers can have" on this microplastic content, Guillaume Duflos, research director at ANSES, told Agence France-Presse (AFP). "This is the first time this type of work has been carried out in France," he emphasized.

The findings revealed the presence of an average of one hundred microplastic particles per liter in glass bottles of colas, lemonades, iced teas and beers; contamination levels five to fifty times higher than those in plastic bottles or cans.

"We expected the opposite result," explains to AFP doctoral student Iseline Chaïb, who carried out this work at the ANSES food safety laboratory in Boulogne-sur-Mer (Pas-de-Calais). "We then noticed that, in the glass, the particles that emerged from the samples were of the same shape, the same color and the same polymer composition, therefore the same plastic, as the exterior paint of the capsules that close these glass bottles," she continues .

The paint on the capsules "has tiny scratches, invisible to the naked eye, probably due to friction between the capsules when they are stored before use," the team of researchers noted, estimating that this "could release particles onto the surface of the capsules."

For water (mineral or natural), the quantity of microplastics was found to be "relatively low, regardless of its container, with an average of 4.5 particles per liter in glass bottles and 1.6 particles in plastic bottles or cartons," explains Anses.