Health. Glass bottles contain more microplastics than plastic bottles.

To counter the health risks and the planet posed by microplastics, many are turning to glass bottles. A good idea? Not so much, according to the surprising results of a study conducted by ANSES.

The research team led by Iseline Chaïb, a doctoral student at the Boulogne-sur-Mer laboratory, analyzed various beverages sold in France: water, sodas, iced teas, wines, and beers. The results are surprising, to say the least.

Drinks such as colas, lemonades and beers packaged in glass bottles contain on average around a hundred microplastic particles per litre.

That's 5 to 50 times more than in plastic bottles or metal cans. " We expected the opposite result ," explains the researcher. This discovery challenges the image we have of glass as a "cleaner" material than plastic.

The origin of these microplastics was quickly identified: they come from the metal caps that seal the bottles. More specifically, it's the paint covering these caps that poses a problem. Scientists discovered two telltale signs.

First, the particles found in the drinks have the same color and chemical composition as the paint on the caps. Second, these caps have tiny scratches, invisible to the naked eye, caused by friction during storage.

The good news is that this contamination can be easily reduced. Researchers tested different methods of cleaning the capsules before closing the bottles. Their experiments showed encouraging results: simply blowing air over the capsules reduced the number of particles from 287 to 106 per liter. Adding a rinse with filtered water and alcohol reduced the number to a further 87 particles per liter.

This discovery opens the door to concrete improvements for the beverage industry. Manufacturers could modify their capsule storage conditions to avoid friction, review the composition of the paints used, or simply integrate a cleaning step into their production process.

Note : In the specific case of water, the quantity of microplastics is 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.