Beer is made up of over 450 different constituents, including macromolecules like proteins, nucleic acids, lipids, and sugars. Many of the proteins that are involved in brewing beer are also responsible for stabilizing the foam on the beer, and also for mouthfeel and flavour stability. These proteins, in combination with polyphenols, also produce the haze in a beer. But haze is also influenced by other, sometimes inorganic products. Yup, on top of water, yeast, hops, and grains, your beer also contains bits of the filters used during brewing, dirt particles, and old bottle labels. Cheers!
The authors of this study have previously shown that honey is contaminated with microplastics, as does regular tap water. They also decided to look at the microplastic contamination of beer.
The researchers looked at 24 different beer brands, including the 10 most popular brands in Germany. They looked at 12 pilseners, 5 wheat beers, and 7 non-alcoholic pilseners. The authors report finding microplastics (in this case, fibers, fragments, and granules) in every single brand of beer, as well as the occasional glass particles and insect remains (right). No one microplastic could be established as the dominant contaminating factor: granular material contributed 5-71% of contamination, fragments contributed 14-87%, and fibers contributed 3-57%, depending on the brand. The authors state that this contamination may come from the manufacturing process, including machinery, but also from the skin and clothing of brewery workers (if that's not enough to put you off your beer...). Importantly, these results show that the human environment is contaminated by microplastics, and that we have no idea what kind of effect they have on human or environmental health. The authors suggest that adherence to principles of hygienic industrial design can help limit the amount of microplastics we are exposed to.
I have a few problems with this study. First, the authors point out twice that their detection method did not distinguish between sand and synthetic plastic granules. They also state that water samples from the Black Forest and Allgäu Alps springs contained sand grains. Both of these springs are used by many of the brewers examined in this study, making it possible that the contaminating granules were actually sand particles. However, sand is not a confounding factor when it comes to the fragments and fibers, and so we can conclude from this study that the beers were contaminated with microplastics, though the type of microplastic remains hazy (pun intended).
Second, I don't think the authors go far enough to stress the potentially harms of this situation. They downplay their findings by saying that microplastics are present in drinking water and common beverages - which is basically saying "hey, at least we all have the same problem!" This could be a great opportunity to influence policy banning microplastics, especially when combined with the data we have coming in on the effects of these products on aquatic ecosystems.