Study finds more microplastics in glass bottles than in plastic ones

Glass bottles containing water, soft drinks, beer or wine contain more microplastics than the equivalent in plastic bottles, according to a study with surprising results published this Friday (20) by the French food safety agency.

Researchers have detected tiny, mostly invisible pieces of plastic all over the world: from the air we breathe to the food we eat, as well as inside the human body.

Although there is no direct evidence that the large-scale presence of plastic is harmful to human health, the finding opens up a new field of research.

Guillaume Duflos, research director at French food safety agency ANSES, told AFP the aim was to "investigate the amount of microplastics in different types of drinks sold in France and examine the impact of different types of packaging".

Scientists found, on average, nearly 100 microplastic particles per liter in glass bottles of soda, lemonade, iced tea and beer.

The result represents between five and 50 times higher than the rate detected in plastic bottles or metal cans.

“We expected the opposite result,” PhD student Iseline Chaib, who took part in the study, told AFP.

The detected samples appeared mainly on the packaging lids.

“We found that, in the glass, the particles detected had the same shape, color and polymer composition – therefore, the same plastic – as the paint on the outside of the caps that close the glass bottles,” he explained.

The paint on the lids also showed “small scratches, invisible to the naked eye, probably due to friction between the lids when they were stored,” the team of researchers highlighted.

In the case of water, both natural and mineral, the amount of microplastics was relatively low in all cases: between 4.5 particles per liter in glass bottles and 1.6 particles in plastic bottles.

The wine also contained few microplastics, even in glass bottles with caps.

Duflos said the reason for the discrepancy “still needs to be explained”. Soft drinks, however, contained almost 30 microplastics per litre, lemonade 40 and beer around 60.

As there is no reference level for a potentially toxic quantity of microplastics, it is currently not possible to say whether these numbers pose a health risk, ANSES said.

However, beverage manufacturers could easily reduce the amount of microplastics released from bottle caps, he added.

The agency tested a cleaning method that involved blowing the caps with air, then rinsing them with water and alcohol, which reduced contamination by 60%.

The study published by ANSES was published last month on the website of the Journal of Food Composition and Analysis.

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