The filtering process may make your beer look nice and clear—but it may also be adding traces of arsenic to your booze. Researchers found arsenic in hundreds of samples of the stuff; some had more than 25 parts per billion, more than twice the US standard for water, NPR notes. Still, experts aren't exactly flipping out. "We already knew that," says one. "The levels shouldn't be alarming, because it's the kind of thing you see in dust or air."
It may just be more precise testing that's revealing the arsenic, he adds. Beer and wine are often filtered using a mined substance called diatomaceous earth, a powder that comes from the tiny algae fossils and could be the arsenic culprit. "People in general will make positive quality associations with clearer beverages," says a professor. Wine makers, however, have been using diatomaceous earth less because of its silica, which can be harmful to breathe, notes a vintner.