Microplastics, tiny particles of plastic, are ubiquitous and pose a threat to human health. A study released by the French food safety agency on June 20 revealed a surprising discovery: beverages in glass bottles contain more microplastics than those in plastic bottles. This unexpected finding has raised concerns among researchers.
The study, conducted by the French Agency for Food Safety, Environment and Labor (ANSES), investigated the levels of microplastics in various types of beverages sold in France and examined the potential impacts of different containers.
Researchers found that soda, lemonade, iced tea, and beer bottled in glass containers contain approximately 100 microplastic particles per liter on average. This is 5 to 50 times higher than the levels detected in plastic bottles or metal cans.
Iseline Chaib, a doctoral student involved in the study, expressed surprise at the results, stating, “It is the opposite of what we expected.”
She noted, “We noticed that the particles extracted from samples in glass bottles had the same shape, color, and polymer composition as the paint on the outer surface of the glass bottle caps, indicating that they are the same type of plastic.”
According to ANSES, the characteristics of these plastic particles led them to conclude that the particles likely originate from the metal bottle caps, more specifically from the paint on the caps.
In addition to the clues provided by Chaib, researchers at ANSES identified another potential source of microplastics—tiny imperceptible scratches on the paint of the bottle caps, likely caused by friction between caps during storage before use. This friction releases plastic particles from the cap surface, believed to be the source of the microplastics found.
When categorized by beverage type, both still and carbonated water showed relatively low levels of microplastics. Bottled water in glass containers contained 4.5 microplastic particles per liter, while plastic bottled water contained 1.6 particles per liter. Even wine, whether in a capped glass bottle, had minimal levels of plastic particles.
However, glass-bottled soda contained around 30 plastic microplastics per liter, lemonade in glass bottles had 40 particles per liter, and beer in glass bottles contained 60 particles per liter.
ANSES mentioned that without established reference standards for the acceptable levels of potentially toxic plastic particles, it is difficult to assess the health risks associated with these findings. Nevertheless, beverage manufacturers can easily reduce the amount of plastic particles shed from bottle caps.
The agency tested a cleaning method involving blowing air onto the bottle caps, followed by rinsing with water and alcohol. This approach resulted in a 60% reduction in microplastic particles.
ANSES also suggested alternative methods for improvement, such as changing the storage conditions of bottle caps to prevent friction or altering the composition of the paint used on the caps.
The research findings were published in the Journal of Food Composition and Analysis, shedding light on the prevalence of microplastics in beverages and proposing strategies to mitigate their impact.