Why is there arsenic in your beer? © ShutterstockThe Germans take the purity of their beer seriously. Back in the 16th century the Reinheitsgebot, or beer purity law, specified that the only ingredients that could be used in beer were water, barley and hops. Once it was realised that yeast was involved in the brewing process that was allowed as well. Today, the Provisional German Beer Law allows slightly different components but it certainly doesn't specify that arsenic can be added to the beer. Mehmet Coelhan of the Weihenstephan research centre at the Technical University of Munich, Germany, however, has...