If you are concerned about ingesting microplastics and choose to reach for glass bottles at the store, you should check what type of caps they have first. A new study has revealed that glass containers often have more microplastics in them than others and researchers think caps are the reason why.
According to authors of the French study published last month by HAL Open Science, the research was conducted to “investigate the level of microplastic contamination in water, soft drinks, beer and wine.” They found that glass bottles were the most contaminated with microplastics.
AFP reported that the researchers found that microplastics contamination in glass bottles was five to 50 times higher than the rate detected in plastic bottles or metal cans. PhD student Iseline Chaib, who conducted the research told the outlet that her team expected “the opposite result.”
Per the National Oceanic and Atmospheric Administration, microplastics are plastic pieces less than five millimeters long which can be harmful to our ocean and aquatic life. It is a common form of marine debris.
Regarding the microplastic contamination in glass bottles, the researchers said “caps were suspected to be the main source of contamination, as the majority of particles isolated in beverages were identical to the color of caps and shared the composition of the outer paint.” Additionally, the study results showed that glass wine bottles with cork stoppers were an exception.
“Analysis of the paint on the metal cap revealed that it was mainly composed of polyester, like the particles isolated from glass bottles, which mainly belong to the polyester class,” the study authors explained. “Therefore, it was hypothesized that these particles could originate from the cap.”
More experiments were then carried out to find a method to lower cap-related contamination. These experiments included cleaning and blowing the caps. Researchers believe small scratches found on the caps may release the particles.
While the AFP noted that “there is still no direct evidence that this preponderance of plastic is harmful to human health,” some research has indicated that the pollution can impact humans.
This February, Audacy reported on research that indicated humans might have as much as a spoonful of microplastics in their brain. In brains with documented dementia diagnoses there was greater accumulation of microplastic observed. However, researchers said that “data are associative and do not establish a causal role for such particles affecting health.”