A surprising new study released by France's food safety agency on Friday has found that beverages sold in glass bottles including water, soda, beer, and wine contain more microplastics than those in plastic bottles.

Researchers have discovered these tiny, mostly invisible plastic particles everywhere from the air we breathe to the food we eat and even within the human body. While there is still no direct evidence that this widespread plastic exposure is harmful to human health, a growing body of research is investigating its extent and potential risks.

Guillaume Duflo's, research director at the French food safety agency ANSES, told AFP that the study aimed to "assess the quantity of microplastics in various types of beverages sold in France and evaluate the influence of different packaging materials."

The findings were unexpected. Glass bottles of soft drinks, lemonade, iced tea, and beer contained an average of about 100 microplastic particles per liter, five to 50 times more than those found in plastic bottles or metal cans.

“We expected the opposite,” said PhD student Iseline Chaib, who led the research. She explained that further investigation revealed the particles matched the color, shape, and polymer composition of the paint used on the caps sealing glass bottles. Microscopic scratches likely caused by friction during storage appeared to be shedding plastic particles from the painted surfaces of the caps.

Still Safe to Sip?

Water both still and sparkling had relatively low microplastic levels across all container types, ranging from 4.5 particles per liter in glass to 1.6 in plastic. Wine also showed minimal contamination, even when bottled with the same type of caps. The reason for this difference "remains to be explained," Duflo's noted.

In contrast, soft drinks contained about 30 particles per liter, lemonade 40, and beer around 60.

Because there is currently no reference point for what constitutes a harmful level of microplastics, ANSES could not conclude whether the levels found pose a health risk. However, the agency emphasized that drink producers could take simple steps to reduce contamination. One cleaning method, involving blowing caps with air and rinsing them in water and alcohol, reduced microplastic presence by 60%.

The full study was published last month in the Journal of Food Composition and Analysis.